Apparatus and method for inserting a continuous and solid joint strip into plastic concrete



Dec. 3, 1968 A. LUSK 3,413,901

APPARATUS AND METHOD FOR INSERTING A CONTINUOUS AND SOLID JOINT STRIP INTO PLASTIC CONCRETE 1O Sheets-Sheet 1 Filed March 16, 1967 INVENTOR. AFT/#01? J. 4 0.5%

Dec. 3, 1968 A. l. LUSK 3,413,901

1 APPARATUS AND METHOD FOR INSERTING A CONTINUOUS AND SOLID JOINT STRIP INTO PLASTIC CONCRETE Filed March 16, 1967 10 Sheets-Sheet 2 INVENTOR. 42mm? J. 10x4 Dec. 3, 1968 A. l. LUSK 3,413,901

APPARATUS AND METHOD FOR INSERTING A CONTINUOUS AND SOLID JOINT STRIP INTO PLASTIC CONCRETE Filed March L6, 1967 10 Sheets-Sheet 3 INVENTOK AIQTl/Z/P J1 0.57.

Dec. 3, 1968 A. l. LUSK 3,413,901

APPARATUS AND METHOD FOR INSERTING A CONTINUOUS AND SOLID JOINT STRIP INTO PLASTIC CONCRETE l0 Sheets-Sheet 4 Filed March 16, 1967 12/ Fifi";

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INVENTOR.

Dec. 3, 1968 A. I. LUSK 3,413,901 OR INSERTING A CONTINUOUS A JOINT STRIP INTO PLASTIC CONCRETE ND SOLID l0 Sheets-Sheet 5 w m 05 4005 c7 v M0702 I 7 654/? 554 50% $5550 a 50X 550055? v a \w: fi Era 1/. 4,

INVENTOR. 4197/ /01? J: Ll/SK ATTOF/VEVJZ Dec. 3, 1968 A. LUSK 3,413,901

APPARATUS AND METHOD FOR INSERTING A CONTINUOUS AND JOINT STRIP INTO PLASTIC CONCRETE Filed March 1.6, 1967 10 Sheets-Sheet 6 SOLID PA/EUMA 776' 671962? A 4271/0? 5 2 EC; 161

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Dec. 3, 1968 A. l. LUSK 3,413,901,

APPARATUS AND METHOD FOR INSERTING A CONTINUOUS AND SOLID JOINT STRIP INTO PLASTIC CONCRETE 7 Filed March 15, 1967 10 Sheets-Sheet 7 1 2/2 T 1 0 i! .i /.4 1 O a r I i v f! 180 2// f 1/2 7g 1/ 17 T v 272 175 206 INVENTOR. APR/u? 1 103A.

Dec. 3, 1968 A. I. LUSK 3,413,901 APPARATUS AND METHOD FOR INSERTING A CONTINUOUS AND SOLID JOINT STRIP INTO PLASTIC CONCRETE Filed March 16, 1967 10 Sheets-Sheet 8 INVENTOR. 4877/01? 1. 0.57!

Dec. 3, 1968 A. l. LUSK 3,413,901

APPARATUS AND METHOD FOR INSEHTING A CONTINUOUS AND SOLID JOINT STRIP INTO PLASTIC CONCRETE Filed March L6, 1967 10 Sheets-Sheet 9 INVENTOR. AFT/ 01? I. 05K

.55a 24. BY {4W 4 TTOENEKQ Dec. 3, 1968 A. I. LUSK 3,413,901

APPARATUS AND METHOD FOR INSERTING A CONTINUOUS AND SOLID JOINT STRIP INTO PLASTIC CONCRETE Filed March 16, 1967 10 Sheets-Sheet l0 4/2 PPASSURE INVENTOR. 4277/1/81 03K United States Patent 3,413,901 APPARATUS AND METHOD FOR INSERTING A CONTINUOUS AND SOLID JOINT STRIP INTO PLASTIC CONCRETE Arthur I. Lusk, Santa Ana, Califl, assignor to Industrial Engineering Developments, Inc., Little Rock, Ark., a corporation of Arkansas Continuation-impart of application Ser. No. 468,381, June 30, 1965. This application Mar. 16, 1967, Ser. No. 623,638

57 Claims. (Cl. 94-39) ABSTRACT OF THE DISCLOSURE The present apparatus and method are particularly adapted to insert joint strips or tapes transversely of plastic concrete shortly after it has been extruded from a paving machine during formation of a concrete highway or similar elongated mass or slab of concrete. Some of the major elements or groupings (which, for convenience, will be referred to below as features) disclosed in detail in the specification are as follows, many of such features being cosely interrelated and coacting unobviously with each other as will hereinafter be set forth in detail:

(a) Apparatus is provided which may be employed to cause the strip-insertion head to travel transversely of the highway at the same time that the entire apparatus is moved longitudinally thereof.

(b) Power-driven means are provided on the apparatus to positively feed (push) the strip in a direction opposite to the direction of traverse of the strip-insertion head, and in precisely timed relationship relative to the speed of traverse, the rate of feeding being such as to create substantially zero resultant strip speed at the point where the strip leaves the insertion head.

(0) The strip-insertion head or blade is so constructed that a fiat (uncorrugated) strip or tape, which is capable of being push-fed, may be caused to change direction in a vertical plane just prior to entering the concrete. Such strip-insertion head also facilitates traverse of the blade through the concrete with minimum disturbance thereof and with maximum insertion speed. In addition, undesired ingress of. grout into the blade is prevented.

(d) Sensing, height-determining, and finishing means are provided to determine the elevation of the head or blade relative to the surface of the concrete, and to fill in and finish over the groove formed in the concrete as the blade moves therethrough.

(e) Means are provided to vibrate the head or blade in a substantially vertical direction. Means are also provided to'vibrate the head or blade, and selected portions of the finishing means, at different frequencies and amplitudes and for different purposes.

(f) Means are provided to cut off the strip or tape after each strip-insertion traverse, and to insure that the remaining strip end .is properly located at the end of the cutting operation and during the return traverse.

(g) Slip-form means are provided at opposite edges of the highway to insure that the strip-insertion head does not break off edge portions of the plastic concrete.

Cross reference to related application This application is a continuation-in-part of my copending application Ser. No. 468,381, filed June 30, 1965, for Apparatus and Method for Inserting a Continuous and Solid Joint Strip into Plastic Concrete, and Joints Formed Thereby, now abandoned.

Background of the invention and brief summary thereof During a period of many decades, a vast amount of effort has been expended in attempts to form, in a practical and satisfactory manner, transverse joints between adjacent sections of a concrete highway or other concrete slab. Many types of apparatus have been invented, and have been adapted to insert an enormous variety of materials and substances into the plastic (uncured) concrete in order to create planes of weakness and thereby control the locations of the cracks formed in the concrete upon curing thereof. For example, it has been proposed to insert mastics, steel strips, paper, plastic, sand, and numerous other materials and substances into the concrete to thus form the desired planes of weakness.

Despite the great amount of activity in the indicated field, the prior-art apparatus and methods were so impractical, unworkable, expensive, inoperative and unsatisfactory that applicant knows of none which is widely employed in forming concrete highways at the present time. Instead, such highways are manufactured as continuous concrete ribbons. After the concrete has become hard, it is sawed at spaced points by means of diamond saws.

Although the art of diamond sawing is highly developed, and widely practiced, it is subject to major deficiencies in that it is extremely slow and expensive and, furthermore, requires a separate operation which must be preformed many hours after the concrete is extruded. It is emphasized that a diamond saw blade is very costly, and will last only a relatively short time. The grooves formed by such saw blades are necessarily wide, so that incompressible solid materials readily enter the grooves (cracks) and result in spalling of the concrete as the concrete thermally expands.

Even more important, however, is the fact that a large number of highways and other concrete slabs which contain such saw cuts are, nevertheless, riddled with undesired random cracks. Such random cracks appear, not only frequently but normally, in the very best of concrete freeways, expressways, turnpikes, etc., despite the presence of diamond saw cuts therein and even prior to the passage of vehicles thereof. Thus, the problem of random cracking is without doubt one of the major problems confronting the builders of concrete highways and the like.

It is emphasized that the same or similar problems relate to concrete (low grade) bases for asphalt highways and to concrete slabs, etc., of various types.

In view of the above general background, the present invention provides an apparatus and method for automatically providing joint strips or tapes transversely of the concrete extruded from a paving machine during formation of a concrete highway or the like. The strips or tapes are inserted rapidly and with minimum disturbance of the concrete. The strips thus inserted are highly effective to control cracking, yet do not weaken the concrete at regions adjacent the cracks. The widths of the grooves formed in the concrete need be no greater than is created by subsequent thermal contraction of the concrete, so that intrusion of incompressible solid material into the grooves is minimized. Accordingly, there is no spalling of the concrete before or during subsequent use to support motor vehicles.

Reference will next be made to the above-enumerated features (a) through (g), inclusive, it being emphasized that other important features are described in detail hereinafter and, furthermore, that various features (a) through g) (and other features) interrelate or interact with each other in unobvious manners to be decribed below.

Feature (a).-Relative to the above-designated feature (a), prior-art apparatus for forming planes of weakness transversely of concrete highways have been entirely of the start-stop type, wherein strip-insertion occurred during a hiatus in the forward progress of the apparatus along the highway. However, as the speed of operation of the concrete extrusion apparatus increases, there will be a progressively greater need for fast-operating strip inserters which can maintain their forward travel along the highway during the traverses of the strip-insertion head thereacross. Thus, and particularly When a strip-insertion head is adapted to effect a traverse at a very high speed, there is no conceivable concrete extrusion apparatus which can operate faster than the strip inserter. Accordingly, the strip-insertion apparatus will not be a limitation on the forward speed of the extruder. The present invention provides, in at least one of its embodiments, an apparatus which can maintain forward progress along the highway at all times, this being because of the incorporation therein of elements which are timed and oriented in a predetermined manner which permits continuance of forward progress, with no disruption or plowing of the concrete any more than would be the case if forward progress were stopped during the strip-insertion traverses.

Feature (b).Relative to the above-designated feature (b), it was common in the prior art to unroll joint strip or tape from a storage reel by anchoring one end of the tape and then permitting the tape to be unreeled or unwound from the reel in response to forward progress of the insertion apparatus along a highway or the like. HOW- ever, in the case of apparatus for inserting strip transversely of the highway, this means that a clamping operation must occur prior to each strip-insertion traverse, with consequent necessity for a complex clamping mechanism and/or additional manual labor. Furthermore, the tension created in the tape as it is pulled from the reel causes stretching of the tape and also variations in the elevation thereof, it being pointed out that the stretched tape normally extends in a straight line whereas the elevation of the surface of a highway may change (as in crowned highways). When a tape is inserted into the plastic concrete in stretched condition, it tends to creep or contract after insertion, which creates problems one of which is that the tape may float upwardly out of the concrete instead of maintaining the desired injection depth.

The tendency of the tape or strip to stretch and creep is augmented by the fact that, in order to be pulled around a corner as the downwardly-traveling tape moves into the horizontal plane adjacent the surface of the I highway, the tape employed was (in prior-art apparatus) necessarily relatively elastic, stretchable, etc., which type of tape has much plastic memory and therefore attempts to assume its original length and condition subsequent to insertion.

In accordance with the present invention, the tape is not anchored but instead is positively fed, or pushed, rearwardly out of the strip-insertion head by a drive mechanism. The rate of feed effected by the drive mechanism is precisely correlated to the rate of travel of the head relative to the concrete, in such manner that zero resultant speed is achieved. Thus, for example, if the head is moving at a rate of about one and one-half feet per second in a predetermined direction, and the tape is being fed at this same rate in precisely the opposite direction, the resultant speed of the tape (relative to the concrete) will be zero, and the tape will emerge from the stripinsertion head in a stress-free manner which eliminates the need of clamping and does not result in creep, floating, etc.

Feature (c).-Referring next to feature (c) specified above, it should be understood that in order to be pushed out of the strip-insertion head as stated in the preceding paragraphs (instead of being pulled out as was the case in prior-art apparatus), the tape employed should be capable of resisting longitudinal compression. A relatively inelastic tape is desirable because it is substantially immune to stretching, creeping, etc. A major problem relates to the bending of such a tape around a corner in a vertical plane, it being understood that the axis of the tape when moving from the reel to the concrete must necessarily extend downwardly whereas the axis of the tape when in the concrete must extend generally horizontally (parallel to the concrete surface). Reference is made to the tape axis because the tape itself, when in the concrete, lies in a generally vertical plane.

Applicants first solution to this problem was to employ a special strip or tape which was pre-corrugated, the corrugations running perpendicularly to the tape axis. The tape itself was sufficiently stiff to be pushed rearwardly through the insertion head, and the corrugations permitted the necessary bending around a corner in a vertical plane. However, the amount of tape which could be stored on a reel was vastly less than the amount of uncorrugated tape which could be stored thereon, and the cost of corrugated tape Was substantially more than the cost of uncorrugated tape. Furthermore, the corrugations resulted in problems relative to feeding and, in some cases, creepingbecause of the fact that a corrugated tape can be stretched and compressed (somewhat) longitudinally of its axis.

Applicants later solution to the problem of bending a strip or tape (including those which are relatively inelastic) around a corner was to provide a uniquely-shaped strip-insertion blade which corrugates or scallops portions of a fiat (not pre-corrugated) tape in situ. Such stripinsertion blade or head is characterized by the presence of undulations or scallops in predetermined portions thereof, being so constructed that the tape may be pushed therethrough in a relatively frictionless manner which does not create compression or stretching of the tape. The amount of tape which may be stored on the reel is multiplied, the cost of the tape is minimized, and the problem of creeping and floating of the tape after insertion is eliminated.

Surprisingly, the same strip-insertion blade which solved the problem of turning an uncorrugated tape around the necessary corner during introduction into the concrete also produced other important advantages. These include reducing the amount of disturbance of the concrete caused by traversing the blade therethrough, reducing the power required to push the blade through the concrete, increasing the speed of traverse of the blade through the concrete, and preventing the undesired ingress of grout into the outlet end of the blade at various times during the operation (which grout would otherwise create a wearing and binding problem).

An additional surprise was that the strip or tape (not pre-corrugated) could be pushed through the head (as described above, feature (b)) with drastically less force than required to pull the tape therethrough, and with no damage to or jamming of the tape.

Feature (a).-Relative to feature (d) specified in the abstract of the disclosure, the problem of height control of the strip-insertion blade relative to the surface of the wet concrete is important and was very difficult of solution. It is desired that the axis of the tape be exactly parallel to the surface of the highway, which surface is frequently crowned or irregular and is formed of concrete having different characteristics. A further important prob lem relates to the filling in of the groove created by the blade during traverse, and the finishing over of the surface of the highway adjacent the injected tape, at a high rate of speed and without disturbing the strength characteristics of the concrete. A good surface finish must be provided which substanttially disguises the location of the tape, which finish is preferably provided without the necessity of :a trailing screed. More importantly, the groove must be filled in a void-free manner and one which maintains the concrete at full strength.

The second embodiment of the present invention solves the above problems by providing a special sensing shoe in advance of the insertion blade, and by providing special finishing trowels and a float therebehind. The sensing shoe operates in conjunction with a pneumatic circuit to control precisely the elevations of the blade, and of the finishing trowels and float, relative to the highway surface. The relationship is such that the control is very precise and is characterized by the absence of hunting and by the ability to effect control even on relatively wet highway surfaces. The rate of groove filling-in, and surface finishing, can be very high, yet the structural integrity of the concrete is maintained so that spalling thereof near the resulting crack is prevented.

Feature (e).Relative to feature (e) designated above, applicant has discovered that if the strip-insertion head is vibnated in a generally vertical direction and in one range of frequencies and amplitudes, and if only a certain portion of the finishing means is vibrated and in another range of frequencies and amplitudes, then the rates of strip-introduction and subsequent surface finishing are maximized while the characteristics of the concrete are also maximized. The operation is such that the aggregate is not separated from the sand and cement at portions adjacent the inserted tape, which provides the very important result of maintaining the strength of the concrete and preventing spalling as the result of major stresses created when trucks, etc., are driven over the highway.

Feature (f).Relative to feature (f) specified in the abstract of the disclosure, it is important that automatic means be provided not only to cut off the transverse joint strip after each traverse, but also to precisely position and locate the remaining end (i.e., the strip end still connected to the insertion apparatus-not in the concrete) in the desired manner. The apparatus for accomplishing this must be immune to such factors as high wind, etc., and should provide a minimum amount of excess tape at each edge of the highway. Furthermore, the cutting apparatus must not jam the tape and perhaps cause binding thereof in the strip-insertion head.

In accordance with the first embodiment of the invention, applicant provided a relatively large and complex cutting :and holding mechanism which performed the operation satisfactorily but which (in addition to its complexity and size) left a relatively large amount of tape adjacent at least one edge of the highway. In accordance with the second embodiment, a highly simple cutting mechanism is provided immediately adjacent the discharge end of the strip-insection head, so that the head itself maintains the tape in position during the return traverse across the highway. The cutting mechanism is so constructed that tape jamming will not result and, furthermore, is constructed in such manner that there will be very little excess tape adjacent either edge of the highway.

Feature (g).Relative to feature (g) specified above, conventional concrete extruders incorporate slip forms and employ concrete which is sufficiently stifi that the edge portions will maintain their continuity (without permanent forms) even after the slip forms are no longer adjacent the edges. However, when a transverse strip-insertion head is entering, and especially when such head is leaving, the edge of the highway there are created stresses which may break down the edge regions adjacent the transverse'strips. Accordingly, the present invention provides additional slip forms which are employed in conjunction with, and correlated to, the transverse strip-insertion apparatus in such manner that the possibility of breaking down of the edges of the highway is eliminated.

Brief description of the drawings FIGURES 1-16, inclusive, relate to the first embodiment of the present invention. FIGURES 17-27, inclusive, illustrate the manner in which the apparatus of the first embodiment is modified in order to form the second embodiment of the invention.

FIGURE 1 is an isometric view of a first embodiment of a strip insertion apparatus constructed in accordance with the present invention;

FIGURE 2 is a top plan view of the showing of FIG- URE 1, but omitting a showing of the prime mover;

FIGURE 3 is an enlarged end elevation of the apparatus, as viewed from station 3-3 indicated in FIGURE 2;

FIGURE 4 is an enlarged elevational view of the carriage and the strip-insertion head, as viewed from station H of FIGURE 2, the strip-storage reel or drum being shown in phantom in order to permit illustration of the Scotch yoke mechanism;

FIGURE 5 is a sectional view illustrating portions of the carriage and head, the section being taken on line 5-5 indicated in FIGURE 4;

FIGURE 6 is a view corresponding generally to the lower portion of FIGURE 5 but with various elements omitted in order to facilitate illustration of the apparatus for effecting vibration of the strip-insertion head;

FIGURE 7 is a perspective view illustrating the stripinsertion head, major portions of the strip-feeding means, the strip cutting and clamping means, and the troweling shoes which also aid in determining the elevation of the insertion head;

FIGURE 8 is a fragmentary sectional view, taken generally in the region indicated at 88 in FIGURE 4, and showing the strip-cutting land strip-clamping means in both closed and open positions;

FIGURE 9 is a horizontal sectional view on line 9-9 of FIGURE 8;

FIGURE 10 is a fragmentary plan view showing a slipform element at one end of the apparatus, such slip-form element being further adapted to clear from the paths of the tires excess concrete left by the extruder;

FIGURE 11 is a schematic sectional view, taken generally at line 1111 of FIGURE 3, illustrating additional portions of the means for driving the carriage in timed relationship to the forward progress of the apparatus along the highway;

FIGURE 12 is a fragmentary vertical sectional view, taken on line 1212 of FIGURE 5, showing the overrunning or one-way clutch incorporated in the drive for the joint strip;

FIGURE 13 is a vertical sectional view, taken generally on line 13-13 of FIGURE 4, showing the joint strip as it moves through the injector head;

FIGURE 14 is a sectional view of a completed joint, including the joint strip and the crack therebeneath;

FIGURE 15 is a view schematically illustrating the pneumatic circuit which associates an air pressure source with the head-supporting means, the strip cut-off and clamping means and the brake for the drum;

FIGURE 16 is a horizontal sectional view taken on line 1616 of FIGURE 5 and indicating in phantom lines the location of the beam or track;

FIGURE 17 is a side elevational view which corre sponds to the lower portion of FIGURE 4 but which illustrates an improved strip-insertion head or blade and related sensing and finishing means, forming the second embodiment of the present invention;

FIGURE 18 is a front elevational view of the showing of FIGURE 17;

FIGURE 19 is an isometric view of the strip-insertion head and related apparatus, corresponding generally to FIGURE 7 but showing the second embodiment instead of the first;

FIGURE 20 is a fragmentary vertical sectional view which corresponds generally to FIGURE '6 but illustrates the second embodiment, the vibration means for the strip insertion blade or head being shown schematically;

FIGURE 21 is a fragmentary horizontal sectional view on line 2121 of FIGURE 17, showing the control means for the fluid cylinder which controls the height of the blade and the associated apparatus;

FIGURE 22 is a fragmentary sectional view on line '7 2222 of FIGURE 17, showing the positive feed means for the uncorrugated joint strip;

FIGURE 23 is an isometric view illustrating the stripinsertion head or blade of the second embodiment;

FIGURE 24 is a horizontal sectional view taken generally along line 2424 of FIGURE 18;

FIGURE 25 is a view corresponding generally to FIG- URE 5 but showing the second embodiment, portions of the apparatus shown in FIGURE 5 being omitted from FIGURE 25;

FIGURE 26 is a fragmentary isometric view of the tape-cutting means of the second embodiment; and

FIGURE 27 is an enlarged sectional view of the stripinsertion head, taken at line 2727 indicated in FIG- URE 23.

DESCRIPTION OF THE FIRST EMBODIMENT, FIGURES 1-16, INCLUSIVE The present apparatus and method will be described as employed in inserting a solid joint strip or tape 10 into a highway or road 11 formed of plastic (wet and uncured, but normally a relatively stiff mix) concrete. It is to be understood, however, that the apparatus and method may be employed relative to other concrete slabs, for example the floors of buildings, the supports or substrates for asphalt highways, etc. Thus, use of the term highway in the appended claims is not to be interpreted as limiting the scope of such claims.

Preferably, the present apparatus is located immediately to the rear of the concrete extruder (including slip forms) used in highway construction. Although the apparatus will be described herein as connected to and thus propelled by the extruder apparatus, it is strongly emphasized that the apparatus may be self propelled as by providing suitable drive means for at least one wheel. An extruder apparatus, or other prime mover, is indicated schematically at E in FIGURE 1, having an engine schematically shown at M.

Stated in a general manner, the present apparatus comprises a bridge which spans the highway 11 and is adapted to be propelled longitudinally thereof, such bridge carrying a carriage adapted to insert a transverse joint strip into the plastic concrete forming the highway. The apparatus further comprises means to drive the carriage transversely of the higway in timed relationship to the speed of the bridge longitudinally of the highway, the result being that the strip may be inserted to form a transverse joint without at any time stopping the forward movement of the bridge along the highway. Additionally, the apparatus comprises means to regulate automatically the height of the strip-insertion head relative to the upper surface of the concrete, so that variations in the elevation of such upper surface will not alter the degree of insertion of the strip into the concrete.

In accordance with another important feature of the apparatus, means are provided to drive the insert strip in timed relationship to the movement of the bridge longitudinally of the highway, and to the movement of, the carriage transversely thereof. Such means effects pushing of the strip into and through the strip-insertion head, the result being that there is little or no stretching and consequent creeping of the strip, and no need for any anchoring of the strip at any time. The strip or tape is continuous, being cut (after insertion) at a point adjacent the edge of the highway by an automatic cutting and holding means provided on the apparatus.

An important feature of the first embodiment resides in the joint strip itself, and in the joint formed in the concrete after the strip is inserted therein. The strip is corrugated in a direction perpendicular to the longitudinal strip axis, so that the corrugations are vertical after the strip is inserted into the concrete. The corrugated strip combines with the strip-feeding means during pushing (as distinguished from pulling) of the strip out of the insertion head. Thus, for example, the use of the corrugated strip 3 permits the strip to be turned from a downwardly-inclined orientation to a horizontal orientation in a space sufficiently short that there will be insufficient friction to cause the strip to bind in the insertion head.

The resulting joint formed at each strip upon curing and aging of the concrete has been found to include a highly desirable crack beneath the full length of the strip, and in the complete absence of cracks between adjacent strips. Thus, the need for sawing of the concrete is eliminated.

Proceeding first to a description of the moving bridge, this is illustrated to comprise a main span or track portion 12 the ends of which connect with truck portions 13 and 14 which move along the ground adjacent each edge of highway 11. The illustrated track or span 12 comprises an I-beam the ends of which are pivoted at pintles 16 to the frames of trucks 13 and 14. Such truck frames are substantially identical to each other, and each comprises a horizontal element 17 along which a sleeve means 17a (which supports pintle 16) is adapted to be adjusted through a limited distance. Two wheels 18 are provided on each truck, one below each end of the frame element 17. Such wheels are rotatably mounted in bifurcated brackets 19 which are pivoted at 20 to the frame ends. Such brackets are locked, at one of several desired pivoted positions, by means of bolts 21 which extend through holes in the frame.

Referring particularly to FIGURE 3, the truck 13 is shown in its normal position, with the wheels 18 (which are preferably provided with pneumatic tires) resting on the roadbed adjacent the edge of highway 11. By removing the illustrated bolts 21 and re-inserting them in holes 22 and through the frame ends, the brackets 19 may be pivoted about points 20 to lower the associated beam end through a predetermined distance. Such distance is equal to the thickness of a conventional highway 11. Lowerin g of one of the ends of the beam relative to the wheels may be effected, for example, when a second strip of highway 11 is to be laid adjacent a previously formed and cured highway. In such a situation, the elevated wheels (and thus lowered beam) ride on the previously cured highway strip instead of on the roadbed adjacent the highway.

Shifting of sleeve means 17a effects a precise or vernier adjustment of the angle of beam 12 relative to the longitudinal axis of the highway, for purposes to be described hereinafter. Means, not shown, are provided to lock sleeve means 17a at any adjusted position on element 17. It is to be understood that various other adjustment means may be provided. Thus, for example, means (not shown) are provided to raise and lower each pintle 16 through any desired distance, in order to adjust the elevation of the beam or track 12 above the surface of highway 11.

In the illustrated embodiment, the portion of the apparatus spanning the wet concrete 11 comprises not only the main span or track 12 but also forward and rear spans 2.3 and 24 which are suitably connected, respectively, to the forward and rear ends of the horizontal frame elements 17. Thus, elements 17 and 2324 form a rigid rectangular frame. Elements 23 and 24 remain generally parallel to beam 12 at all times, including during and after vertical adjustment of wheels 18 as described above relative to FIGURE 3. Both of such spans 23 and 24 may support catwalks and other apparatus, some of which will next be described.

Forward span 23, in the illustrated embodiment, has connected thereto a drawbar 26 adapted to be pivotally connected to the associated extruder E. Mounted at one end of the forward span is a source of power which is indicated schematically at 27. Such power source may comprise, for example, a gasoline engine (not shown) adapted to drive an air compressor (not shown) and also a hydraulic pump (not shown) to thus supply the requirements of the apparatus for air and hydraulic fluid under pressure. in addition, the power source 27 may comprise a generator driven by a gasoline engine, and serving to provide electrical power adapted to be employed for purposes such as remote control of various devices.

The air compressor connects to the interior of the forward span 23, which is formed of tubing adapted to contain air under pressure. Air from such span interior (which serves as an air receiver) passes through a master air-control valve 28 (FIGURE 1) and flexible hose 29 to pneumatic apparatus on the carriage. Such hose is illustrated as being hung on a pivotally-mounted angle bar 31 adapted to support the hose as the carriage moves back and forth between the ends of track 12. The forward span (air receiver) 23- is connected, through a suitable pipe (not shown), with the rear span 24 (also formed of tubing) to charge the same with air. As will be indicated hereinafter, air may thus be bled from such rear span for operation of equipment such as vibrators and the like.

Proceeding next to a general description of the carriage, Which is denoted generally by the reference numeral 32, this is best illustrated in FIGURES 4 and to comprise a generally C-shaped frame 33 on which are mounted eight rollers 34. Four of such rollers ride on the lower surface of the upper flange of the I-beam 12, on opposite sides of the web thereof, whereas the remaining four rollers are supported on the upper surface of the lower flange. Thus, the carriage 32 may be driven along track 12, in a relatively frictionless manner, due to operation of drive means to be described hereinafter.

Mounted in vertically-movable and parallel relationship on carriage 32 are tubular shafts or connectors 36. Such shafts extend slidably through an upper set of bearings 37 and a lower set of bearings 38, such bearings being mounted, respectively, on the upper and lower portions of the C-shaped frame 33. The lower ends of the shafts 36 connect rigidly to a horizontally-disposed support plate 39 for various major components of the apparatus, including the previously indicated strip-insertion head, which is shown at 41.

Shafts 36, and thus the support plate 39 and connected apparatus, are supported and vertically moved in response to the conjoint action of three means next to be described. The first such means is a pneumatic cylinder 43 the lower end of which is pivotally connected at 44 (FIGURE 5) to a bracket 45 on frame 33. The upper end of cylinder 43 is pivotally connected to a lug 46 on a yoke 47 to which the upper ends of both shafts 36 are bolted or otherwise secured. Thus, introduction of air under pressure into the lower end of cylinder 43 operates to extend the same and thereby lift yoke 47 and the connected shafts 36 and support plate 39.

The second of the indicated means for moving the shafts 36 vertically is a Scotch-yoke mechanism 48. Such mechanism comprises a generally rectangular and verticallyoriented plate 49 having at the upper corners thereof upper bearing portions 51 which are located above the bearings 38 and which receive, respectively, the shafts 36. Provided at the lower corners of plate 49 are lower bearing portions 52, such bearing portions also receiving the shafts and being disposed below the bearings 38.

Plate 49 and the bearings thereon cooperate with collars 53 which are rigidly mounted on shafts 36 above bearing portions 51. Thus, upon elevation of plate 49 until the upper surfaces of bearing portions 51 engage collars 53 such collars and the shafts 36 will be elevated. It is to be remembered, however, that the force required to eflect such elevation is determined largely by the amount of pressure in cylinder 43 (FIGURE 5).

The indicated upward movement of the plate 49, and subsequent downward movement thereof, are effected by a drive chain 54 mounted longitudinally of the span or track 12 and which serves to shift the carriage 32 longitudinally of the track to traverse the highway 11. Plate 49 is connected to drive chain 54 by means of a master link 56 which is preferably, as shown in FIGURE 5, associated with the plate 49 by means of suitable ball bearings.

The remaining of the above-indicated three means for vertically moving the shafts 36 and apparatus supported thereby comprises large shoes or floats 57 adapted to be supported on the upper surface of the plastic concrete 11. Such shoes or floats 57 are directly mounted to the support plate 39, for example by means of the indicated brackets 58 (FIGURE 7).

As will be stated in greater detail hereinafter, the amount of air pressure in pneumatic cylinder 43 (FIG- URE 5) is correlated to the weight of the shafts 36 and apparatus supported thereby, and also to the characteristics of the plastic concrete 11, in such manner that the shoes 57 will float on the concrete and will automatically adjust the height of the support plate 39 (and thus stripinsertion head 41) in accordance with the elevation of the upper concrete surface. Thus, it is insured that the strip 10 will be inserted a predetermined desired distance into the concrete, despite irregularities in the upper surface and despite factors such as the inclined nature of such upper concrete surface (for example, in the case of crown-type highways).

At the end of a strip-insertion traverse of the carriage, the master link 56 is elevated as the associated portion of drive chain 54 is elevated by one of the sprockets therefor. Thus, and particularly if the pneumatic pressure in cylinder 43 is then increased as will be described, the upper bearing portions 51 on plate 49 bear against collars 53 and lift shafts 36 until the strip-insertion head 41 is spaced above the concrete, the apparatus then being in condition for a return traverse to the opposite side of the highway.

It is to be understood that the collars 53 may be suitably adjusted on shafts 36 (for example, by means of locking devices associated therewith) to permit a desired degree of upward and downward movement of the shafts 36 and the head 41.

The apparatus for effecting vertical movement of the shafts 36 and associated strip-insertion head 41 achieve more than one purpose. Thus, the shoes or floats 57 are so oriented (as best shown in FIGURE 16) that they will effect smoothing or troweling of the region of the plastic concrete into which the strip 10 has been inserted. Stated more definitely, the shoes or floats have portions disposed directly to the rear of (and aligned with) the strip-insertion head. Also, as above noted, the Scotch-yoke mechanism 48 and associated drive chain 54 not only effect vertical movement of the shafts and head, but also elfect horizontal movement thereof along the span or track 12.

It is a feature of the described and lowering the shafts 36 (and connected head 41 and other apparatus) that the vertical movement at each end of the traverse is characterized by substantially uniform acceleration (and deceleration). The acceleration is controlled by the Scotch-yoke mechanism 48 which, for reasons known in the mechanical arts, is a constant-acceleration device. Such constant acceleration, and the associated force exerted by pneumatic cylinder 43, effect a smooth raising or lowering of the head at each end of the traverse, without excessive mechanical shock and without substantial strain on the drive chain 54 and associated sprockets and other parts.

Detailed description of feature (a) specified in the abstract of the disclosure There will next be described the means for driving the chain 54 and thus the carriage 32 and head 41 in precisely timed relationship to the movement of the apparatus longitudinally of highway 11. Such drive chain 54 is mounted between a drive sprocket 60 and an idler sprocket 61 (FIGURE 1) which are located at opposite end portions of beam 12. Both runs of the chain 54 are guided, at points between sprockets 60 and 61, by means of suitable chain guides 62 (FIGURES 4 and 5). Such chain guides may be of conventional construction, being mechanism for raising 1 I mounted on the web and flange portions of the I-beam track 12 as best shown in FIGURE 5.

The means to drive the sprocket 60 in timed relation to the forward movement of the wheels 18 of the apparatus may comprise, for example, an electric (or hydraulic, etc.) motor which is connected by reduction gears (not shown) to wheels 18 to drive the same, and is also connected by reduction gears to sprocket 60 to drive it and thus the associated chain 54 and carriage. With such an arrangement, the device is self-propelled, as above noted, no drawbar 26 and prime mover E (FIG- URE 1) then being required. The gear ratios are so related to each other that the strip-insertion head 41 traverses the plastic concrete 11 without plowing the same, as will be set forth hereinafter.

In the illustrated apparatus, the drive for sprocket 60 and thus chain 54 comprises a hydraulic motor 63 (FIG- URES 3 and 11) which is connected by suitable piping, not shown, to the above-mentioned hydraulic pump contained within power. source 27. Such motor is connected to sprocket 60 through suitable speed-reducer means indicated at 64 (FIGURE 11). One of the wheels 18 (FIG- URE 1) then being required. The gear ratios are so reslipping) manner to be described hereinafter. The wheels 18 are turned due to pulling of the apparatus by prime mover E (FIGURE 1).

Because the relationship between sprocket 60 and wheel 18 (FIGURE 3) is fixed, the speed of operation of the sprocket is controlled by the speed of rotation of the wheel 18 (which may be termed the timing wheel). Thus, the hydraulic motor 63, operating as a booster, does not control the speed of the sprocket 60 but does operate to supply power thereto under the timing control of the wheel 18 and associated mechanism. The hydraulic motor 63 may have associated therewith a bypass means (not shown) to bypass hydraulic fluid during periods when the wheel 18 is stopped or moving relatively slowly.

As shown in FIGURE 3, the hub portion of timing wheel 18 has mounted thereon a sprocket 66 around which is extended a timing chain 67. Such chain extends adjacent suitable idler sprockets to a sprocket 68 which is connected to a gear box 69. As shown in FIGURE 11, gear box 69 is connected by a drive chain to second gear box 70 which, in turn, is connected by suitable sprockets and an additional drive chain to the shaft of sprocket 60.

A clutch mechanism 71, operated by a handle 72 (and/ or by a piston), is provided at the hub of timing wheel 18 (FIGURE 3) and is selectively operable to connect and disconnect the sprocket 66 relative to such wheel.

When clutch 71 is engaged, the timing wheel 18 operates through timing chain 67 to positively control the speed of operation of gear-box means 69 and 70 and thus the speed of driving of the sprocket 60, chain 54 and earriage 32. When clutch 71 is disengaged, the sprocket 60 and chain 54 are driven by the hydraulic motor 63 at an untimed speed. It is to be understood that the lastmentioned mode of operation is not normally employed, the purpose of the clutch 71 being to disengage sprocket 60 from the timing chain 67 when it is desired to move the apparatus along the highway without inserting joint strip therein (for example, during initial orientation and setup of the apparatus). Suitable valve means (not shown) may be provided to cause hydraulic motor 63 to cease operating when desired.

As an example of the way that the various drives may be related or timed, let it be assumed that the desired forward speed of the apparatus along the highway is approximately eight feet per minute (it being understood that the speed may be much greater). The gearing is then so constructed and related that the speed of driving of chain 54 by sprocket 60 will be on the order of fortyeight feet per minute. The joint strip will then be inserted into the concrete along a line which is at an angle relative to a perpendicular to the longitudinal axis of the highway) of about nine and one-half degrees. To accomplish this result, and to prevent undesired plowing of the concrete by the strip-insertion head 41, such head is canted relative to a perpendicular to the longitudinal highway axis at the same angle (approximately nine and one-half degrees).

Fine or vernier adjustments of the angle of strip insertion are effected by shifting one or both ends of the beam or track (span) 12 forwardly or rearwardly, so that the beam 12 is itself at an angle, relative to the longitudinal axis of the highway, which is somewhat different from ninety degrees. Such movement is permitted because of the presence of the pintles 16, and because the frame portions 1711 (FIGURE 3) may be adjusted longitudinally of frame elements 17 as stated heretofore.

To amplify upon the above, it is pointed out that the strip-insertion head 41 is an elongated, narrow element which (when viewed from above) is oriented at an acute angle relative to the longitudinal axis of the beam or track 12 from which it is movably supported. This is best shown in FIGURES 2 and 16, wherein the track 12 is shown as generally perpendicular to the highway axis and the head is at an angle (for example, about nine and one-half degrees) to the track. It is also possible to cause the track to be oblique to the highway axis, and the head perpendicular thereto. Various other angles may be employed, so long as the relationship stated in the following paragraph is adhered to.

To compute (during manufacture of the apparatus) the angle of the head 41 relative to track or beam 12 (when such elements are viewed from above), it is necessary to determine the vector sum of the speed of the apparatus along the highway and the speed of the carriage along the track (the latter speed being fixedly related to the former because of the described drive relationships). The head is then oriented parallel to the resultant found by such vector addition.

With the described construction, the strip-insertion head moves longitudinally and smoothly through the concrete and forms only a narrow groove which is readily and automatically covered by the troweling shoes 57. Such shoes extend over the indicated groove (which contains joint strip 10) as best shown in FIGURE 16. If the described vector relationship were not adhered to, the head would tend to plow (and thus greatly disturb) the concrete by moving laterally instead of purely longitudinally.

Detailed description of feature (b) (first embodiment) specified in the Abstract of the Disclosure In addition to the drive chain 54 which is mounted on one side of the web of beam or track 12, there is mounted on the other side of such web a stationary chain 76 (FIGURE 5) which forms part of the feeding mechanism for insert strip or tape 10. The chain 76 is suitably mounted on the upper surface of the lower flange of the I-beam 12, and has meshed therewith a sprocket 77 which is rotatably mounted on the C-frame portion 33 of carriage 32.

The sprocket 77 is connected through a suitable flexible drive 78 with a feed roller 79 (FIGURES 4, 7 and 12) which is rotatably supported on the support plate 39. Stated more definitely, the shaft of the feed roller 79 is mounted in suitable brackets 80 (FIGURE 7) which depend from an extension of the support plate.

The joint strip 10 is thus fed in response to operation of the elements 77 and 79, as element 77 moves along the stationary chain 76. Such feeding is in perfect timed relationship to the speed of movement of the carriage 32 as it traverses the highway 11 (and also in perfect timed relationship with the forward movement of the entire apparatus along the highway),

Joint strip 10 is fed from a storage roll thereof, such roll being provided on a large reel or drum 81 (FIGURE 5) having a horizontal axle or central shaft 82 which is rotatably supported in ball bearings 83 provided on the upper surface of C-frame 33.

At the end of a strip-insertion traverse across the highway 11, the reel 81 has considerable rotational inertia. Nevertheless, such reel is rapidly stopped by operation of a pneumatic brake which is schematically represented at 84. Such brake incorporates a stationary housing which is fixedly mounted on C-frame 33, and further incorporates means (in the nature of clutch discs) which are responsive to application of air pressure to stop rotation of shaft 82 and thus of the reel or drum 81.

As is best illustrated in FIGURES 4, and 7, the joint strip after leaving reel 81 passes under a first idler roller 86 on support plate 39, thence over a second idler roller 87 thereon, and thence over a third idler roller 88. Thereafter, the strip passes downwardly into a U-shaped bracket 89 having a fourth idler roller 90 rotatably mounted therein, following which the strip passes upwar dly over a fifth idler roller '91 and thence downwardly between the feed roller 79 and a sixth idler roller 92. Roller 92 is adjustably mounted adjacent the feed roller 79 and serves as the back-up or compression roller therefor. In the illustrated embodiment, the back-up idler 92 is shaped as a gear (FIGURE 12) in order to mesh with the joint strip 10 which is corrugated as will be described. Drive roller 79 may be correspondingly gear shaped, or may (for example) be formed of soft rubber and have a relatively smooth surface.

From the feed roller 79 and its associated back-up roller 92, the joint strip 10 is fed into the forward end of head or blade 41, and thus is pushed through such head and out the rear end thereof into the soft concrete 11 as shown in FIGURE 4. Stated more definitely, the strip is pushed rearwardly into the groove formed in the concrete by head 41. It is emphasized that such pushing or expelling of the solid joint strip 10 from the head 41 is markedly different from prior-art constructions wherein the joint strip was first anchored in the concrete and then pulled from the apparatus in response to movement thereof. The present apparatus, wherein the joint strip is pushed out of the head, eliminates the necessity for any anchoring operation and thus makes it practical to achieve such benefits as automatic cutoff of strip sections from a continuous roll (as distinguished from the use of individual and pre-cut strip lengths).

A major benefit achieved by the invention is that the joint strip 10 (where in head or blade 41, and in the concrete) is never pulled and thus stretched. Such stretching is disadvantageous in that the strip then tends to contract (creep), which disturbs the concrete in which the strip is embedded.

The relationship between sprocket 77 (FIG. 5) and the feed roller 79 is so selected that the joint strip 10 will be fed at the same rate of speed as (but in opposite direction to) the resultant speed achieved by the head 41 as it traverses the highway. Because of the above-described vector relationships, such resultant speed is greater than the speed of the head relative to the track. Thus, there is no relative movement between the joint strip (at the portion thereof which enters the highway) and the concrete highway 11. The timed relationship is preferably caused to be so precise that, even if the carriage were merely traversed over the ground as distinguished from over wet concrete, the joint strip 10 would be laid down on the ground and would not be pulled therealong.

Detailed description 0 the strip-insertion head or blade (first embodiment) As best shown in FIGURES 4, 7, 13 and 16, the head or blade 41 comprises an elongated channel which is disposed in a vertical plane and, preferably, has a relatively sharp and closed bottom edge adapted to knife into the plastic concrete. The upper portion of the channel should also be closed, as illustrated. The channel is sufficiently large to loosely receive the joint strip, without bending the same. The entire length of the passage through the channel is straight.

As stated in detail above, the vertical plane in which the head 41 is disposed is not parallel to the track or I-beam 12 but is, instead, somewhat oblique thereto (FIGURE 16) by an angle which is related to the degree of forward progress of the entire apparatus along the highway as the carriage traverses the same.

As shown in FIGURE 4, head 41 is inclined downwardly and rearwardly at an angle sufiicient to cause the forward end of the head to be spaced substantially above the upper surface of the concrete, and the rearward end of the head to be disposed below the surface of the concrete by a distance corresponding generally to the vertical dimension of the joint strip 10. In the illustrated embodiment, the angle of inclination of head 41 relative to a horizontal plane is on the order of fifteen to twenty degrees, but certain other angles may be employed.

It is a feature of the first embodiment that the joint strip or tape 10 is corrugated in such manner that the corrugations are substantially vertically oriented When the joint strip is embedded in the concrete, as illustrated at the left in FIGURE 4. Because the joint strip is corrugated, it may be formed of a material which is Stlfi'lCiently rigid and slippery to be readily fed into and through the head 41, without at any time binding, while still being able to turn the corner (illustrated as approximately fifteen to twenty degrees) at the rear end of the head and as the strip discharges therefrom. Such angular move ment of the joint strip, while lying at all times in a vertical plane, is accompanied by a stretching of the corrugations at the lower edge of the joint strip, and by compression of corrugations at the upper edge thereof.

The axes of the feed roller 79 and the associated backup roller 92 are disposed parallel to each other and in a horizontal plane. Furthermore, such roller axes are generally perpendicular to the vertical plane containing head 41. Thus, the joint strip 10 must twist through approximately a ninety-degree angle in passing between feed roller 79 and the inlet end of head 41. Such ninety-degree twist is readily made, without decreasing the ability of the feed roller 79 to push the joint strip into and through the head 41, because of the corrugated nature of the joint strip.

As a specific example, the joint strip is preferably a cheap material such as polystyrene plastic, being preferably approximately 0.020 inch or 0.025 inch thick. The vertical dimension of the joint strip should be on the order of 20 to 25% of the thickness of the concrete. Thus, in a concrete highway 9 inches thick, the joint strip may have a vertical dimension of approximately 2 inches. The distance between the parallel planes containing the apex portions of the joint strip (opposite sides thereof) may be, for example, on the other of inch.

Description of the head-vibration means (first embodiment) It is an important feature of the present method and apparatus that the head or blade 41 is vibrated vertically, in a predetermined manner, during the entire time the joint strip 10 is inserted into the concrete. For this purpose, and referring particularly to FIGURE 6, the head 41 is not mounted directly to the support plate 39 but instead is associated therewith through suitable suspensi'on and vibration-isolation helical compression springs indicated at 93. Such springs are mounted around the shanks of bolts 94, and bear against the upper and lower surfaces of support plate 39. The clearance holes in plate 39 for such bolts 94 are sufficiently large that there will be no direct contact between the bolts and the plate.

Bolts 94 connect at their lower ends to a bracket 96 to the lower edge of which the head 41 is attached. Such bracket 96 further includes an upwardly-extending por tion 97 which passes through a clearance slot in support plate 39 and sup-ports at the upper end thereof a vibrator 15 element 98 adapted to effect vertical vibration of the as sociated bracket and thus of head 41.

The illustrated element 98 is a piston-type vibrator having a vertically-oriented piston adapted to travel back and forth through a distance on the order of A; inch, in response to pneumatic actuation. The speed of vibration is preferably on the order of 3600 cycles per minute.

In the described manner, the vibrator 98 effects rapid vertical vibration of head 41 but not of the plate 39 and associated portions of the carriage. The vibration is very important in causing the head 41 to move smoothly through the plastic concrete 11, and to displace aggregates away from the path of the head, without at any time causing plowing, upsetting, or other undesired re sults. In addition, such vibration causes the grout portion of the concrete to flow into the furrows between adjacent corrugations of the portion of joint strip previously inserted into the concrete, thus insuring that there will be no voids adjacent the joint strip.

Detailed description of feature (f) (first embodiment) specified in the Abstract of the Disclosure Proceeding next to a description of the automatic cutoff and holding means for the joint strip 10, this is best illustrated in FIGURES 4 and 7-9 and comprises first and second arms 100 and 101 adapted to be pivoted in a vertical plane which is generally perpendicular to the joint being made by the strip 10. Mounted at the ends of arms 100 and 101 are clamping plates 102 and 103 adapted to engage and grip the joint strip 10 at a region spaced rearwardly from the outlet end of insertion head 41. One of such plates, numbered 103 is resiliently mounted by means of helical compression springs 104 (FIGURE 9) which are disposed around bolts 106 extending through a bracket 107 on the arm 100.

Upon downward rotation of the arms 100 and 101 from the position shown in phantom lines in FIGURE 8 (and in solid lines in FIGURE 4) to the position shown in solid lines therein, the clamping plates 102 and 103 resiliently clamp the strip end. At the same time, a shearing knife blade 108 (which is welded to the rear vertical edge of bracket 107) engages and cuts off the strip 10. Such knife blade 108 passes closely adjacent the rear edge of clamping plate 102, so that a shearing action results. The blade 108 may have a serrated or scalloped edge, as illustrated.

The arms 100 and 101 comprise cranks which are fixedly mounted on horizontal parallel shafts 109 and 110, which shafts are suitably journaled in bearings 111. Such bearings are supported from suitable bracket means 112 on the support plate 39. The bracket means 112 also supports meshing one-to-one gear means 113 which are adapted to effect corresponding but oppositelydirected pivotal movement of the arms or cranks 100 and 101. The indicated pivotal movement results from operation of a pneumatic cylinder 114 (FIGURE 8) which is pivotally associated with bracket means 112 and is also pivotally connected to a crank 116 on shaft 110.

Upon introduction of air into cylinder 114 in a manner effecting retraction of the piston thereof, the crank 116 is operated to effect rotation of arm 100 from the solidline position of FIGURE 8 to the phantom-line position thereof. Correspondingly, and because of the meshing relationship of the gear means 113, the arm 101 also moves from the solid-line position to the phantom-line position.

After the head 41 traverses the entire highway 11 during a strip-insertion pass, it moves horizontally out of the edge portion of such highway by a distance which is sufficient that the knife blade 108 will be disposed above the ground adjacent the edge of the highway, and will not be disposed over the highway itself. In other words, a section of strip 10 is held in open air between the concrete, wherein the strip is embedded, and the outlet end of the head 41. Cylinder 114 is then operated to effect the above-described downward pivotal movement of the arms and 101, with consequent cutting of the strip 10 and also gripping of the severed strip end which is nearest the head 41.

The indicated gripping action is continued during the entire time that the head 41 is lifted due to the conjoint action of the above-described Scotch-yoke mechanism 48 and the pneumatic cylinder 43, and during the entire time such lifted mechanism is return-traversed back to the other edge of the highway. Thereafter, and as will be described, cylinder 114 is actuated to effect upward pivotal movement of the arms 100 and 101, so that the clamping action on the strip end is released. A new stripinsertion traverse is then effected across the highway, and the operation thus repeated.

Means are provided to prevent feedin of the strip 10 during the return traverse across the highway while the head 41 is in elevated position, so that there will be no reverse-feeding during the return traverse. Such means is illustrated in FIGURE 12 to comprise an overrunning (one-way) clutch 117 which is incorporated in the drive roller 79. The clutch comprises parts 118 and 119, part 118 being directly connected to flexible drive 78. The elements 118 and 119 are so related that driving of roller 79 will be effected when the sprocket 77 (FIGURE 5) is shifted along stationary chain 76 during a strip-insertion traverse of the carriage, but will not be effected during return movement of the sprocket 77 on the chain 76. Thus, the direction of feeding is such that the drive roller 79 will be driven clockwise (FIGURE 12) during movement of the carriage from left to right (stripinsertion traverse) as viewed in FIGURE 1, but will remain stationary during movement of the carriage from right to left (return traverse) as viewed in FIGURE 1.

Detailed description of feature (g) specified in the Abstract of the Disclosure Referring particularly to FIGURES 2 and 10, there is removably mounted at the lower portion of each of the trucks 13 and 14 a slip-form means 121 adapted to bear resiliently against the plastic concrete 11. Stated more definitely, such means comprises an inner member 122 in engagement with the vertical side or edge 123 of the concrete 11, and an outer member 124 mounted on one of the trucks 13 or 14. Suitable resilient means, indicated at 126 and comprising, for example, telescoped tubular elements containing an elongated helical compression spring, connect the inner and outer members to each other and effect resilient engagement between the inner member and the edge or side 123.

A gap 127 is provided in inner member 122 at the region where the strip-insertion head 41 either enters or leaves the edge of the concrete. In the showing of FIG- URE 10, the position of the slip-form means is that which occurs a substantial period of time after the head has entered the concrete, so that the gap 127 is shown as being advanced relative to the end of the joint. Such movement is permitted because the projecting end of strip 10 is merely flattened against edge 123 by the inner member 122.

The described slip-form means insures against breakage of the edges of the concrete, particularly the concrete edge from which the head 41 emerges at the end of a strip-insertion traverse. Furthermore, the strip-form means performs other beneficial functions such as insuring that excess concrete left by the extruder mechanism will not be picked up by the rear wheels 18.

It has been found that the previously extruded concrete is not marred or disfigured to any great extent by the present strip-insertion apparatus. Thus, as described heretofore, the shoes 57 effectively smooth over the groove made temporarily in response to passage of the head 41 through the concrete. Nevertheless, the apparatus may incorporate trailer means to provide an additional finishing and leveling operation relative to the 1 7 concrete, such trailer means being shown at 131 in FIGURES 1 and 2.

The trailer mechanism is illustrated to comprise one (or several axially adjacent) smoothing float or screed 131 which is pivotally connected to the rear frame component 24 by means of pivot members 132. Furthermore, the float 131 is connected to such member 24 by cylinders 133 (preferably pneumatic) which are disposed in angular relationship to the pivot members 132. Cylinders 133 are suitably associated with the air compressor portion of power supply 27, the relationship being such that the cylinders may be operated to determine the precise elevation of the float 131.

A suitable vibrator 134 is mounted on the float 131 to continuously vibrate the same. Furthermore, means may be provided to effect a slight degree of longitudinal reciprocatiori of the float as the apparatus progresses. For example, one end of the float may be disposed adjacent one of the wheels 18, and cam means may be provided at spaced points on such wheel to effect longitudinal reciprocation of the float.

The apparatus 131-134 provides a smoothing, leveling and finishing operation relative to the concrete into which the strip 10 has been inserted.

Summary of the method, and operation (first embodiment) Stated generally, the method of the invention comprises moving a strip inserter at a predetermined rate and along a line through the upper regions of a slab of plastic concrete, continuously pushing a joint strip through such inserter at a rate equal to such predetermined rate (and in a direction opposite to the direction of push) whereby there is no relative movement between the joint strip and the concrete, and continuously vibrating the strip inserter to aid in displacing the aggregates in the concrete and to aid in setting and embedding of the joint strip therein. The method further comprises employing as the joint strip a length of transversely-corrugated plastic or the like, and maintaining the strip inserter at an oblique angle to the upper surface of the slab so that the strip is caused to turn a corner upon emerging from the inserter. Particularly where the concrete slab is a highway, the method comprises causing the inserter to emerge horizontally from the concrete at the highway edge, then cutting off the strip at the laterally-projecting portion thereof, and thereafter holding the remaining strip end and traversing the inserter over the highway prior to commencement of an additional insertion traverse. The above steps are performedby moving an apparatus longitudinally and continuously along the highway, and traversing the inserter in timed relationship to the forward (longitudinal) movemen-t of the apparatus, the timed relationship and the inserter orientation being such that no plowing of the concrete occurs.

An additional step in the method comprises performing, as a Vernier adjustment relative to the timed relation between the forward movement of the apparatus along the highway and the traversing movement of the strip inserter thereover and therethrough, a step whereby the track or support for the inserter is adjusted to a slightly oblique angle relative to a perpendicular to the longitudinal axis of the highway. Such oblique angle is correlated to the relative movements in such manner that the strip inserter moves longitudinally through the concrete, without laterally displacing or plowing the same.

With specific reference to the apparatus shown in the drawings and described hereinabove, the method of the invention comprises providing a span or track 12 the sprockets 60 and 61 of which are spaced apart sufiiciently far, relative to the width of the highway 11, that the strip-insertion head 41 will enter and leave the highway edges in a substantially horizontal direction. It is to be understood, however, that (particularly in the case of entering the concrete) the direction may be termed tangential in that it may occur when master link 56 (FIG- URE 4) is traversing the lower-left quadrant (FIGURE 4) of sprcoket 60. The invention also comprehends substantially vertical movement of head 41 into the edge portion of the concrete, although this not preferred. The amount of substantially horizontal movement occurring at the end of a strip-insertion traverse should be sufficient to permit the knife blade 108 to cut off the strip 10 at a portion thereof which projects from the edge of the highway.

As previously described in detail, the various drive relationships, and the precise angle of beam or track 12 relative to the longitudinal axis of the highway, are so adjusted that the head 41 may move longitudinally through the concrete, as the bridge (including wheels 18) progresses, in the absence of any movement of the head 41 in a lateral direction relative thereto, so that no plowing of the concrete results. Precise adjustment of the angular position of beam 12 is permitted by the pintles 16, which permit adjustment of the pintle-supporting portions 17a relative to the rigid frame of the apparatus.

Let it be assumed that the carriage 32 is initially adjacent the left or insertion-traverse beginning side of highway 11 (FIGURES l and 2), master link 56 then being adjacent the lower-left quadrant of sprocket 60 (as viewed in FIGURE 4). The strip clamping mechanism (FIG- URES 7-9) is then in its unclamped position, the arms and 101 being generally horizontally oriented. The forward portions of supporting and troweling shoes 57 are then disposed on the edge of the concrete, and determine the elevation of the head 41 (pneumatic cylinder 43 (FIGURE 5) having suflicient air pressure therein to counteract the weight of the apparatus and permit the shoes 57 to thus function).

Movement of the lower run of drive chain 54 to the right, as viewed in FIGURE 4, then causes the entire carriage 32 to move correspondingly. Head or blade 41 is thus propelled through the plastic concrete, in response to such movement and also in response to the vibration action effected by the vibrator 98 (FIGURE 6). Although the head 41 thus moves through the concrete, and simultaneously displaces the large aggregates therein, the strip 10 emanating from the outlet (left) end of the head 41 remains stationary relative to the concrete. This is because, as previously described in detail, the relationship between the drive sprocket 77 (FIGURE 5) and the stationary chain 76, and also relative to the drive roller 79 to which sprocket 77 is connected by the flexible drive 78, are such that the strip is pushed rearwardly out of the head 41 at the same speed that the head moves forwardly through the concrete. In emanating from the trailing end of the head 41, strip 10 turns a corner in a vertical plane, such turning being permitted by the corrugated nature of the strip as described above.

In the stated manner, the entire highway 11 is traversed by the carriage and head, and a strip or tape 10 is inserted to the desired depth into the plastic concrete. The troweling and elevation-determining shoes 57, in riding on the upper concrete surface, cooperate with the pneumatic cylinder 43 in causing the elevation of the head 41 to remain constant relative to the elevation of the upper highway surface. Thus, the head follows slight depressions in the concrete, and also changes elevations when the highway is of the crowned variety.

When the end of a strip-insertion traverse (left to right) is reached, the trailing edge of insertion head 41 leaves the vertical edge of the highway so that a portion of the strip 10 is in midair adjacent the highway. As previously described, a slip-form apparatus 121 (FIG- URE 10) having a gap 127 therein to permit movement of the head 41 therethrough, insures against any breakage of the concrete edge due to movement of the head 41. When the knife blade 108 is disposed above a projecting (not embedded) section of the strip 10, pneumatic cylinder 114 (FIGURE 8) is actuated to shift the arms 100 19 and 101 down to the positions shown in solid lines in FIGURE 8, causing the strip 10 to be cut off and clamped as stated in detail above.

At substantially the same time that the cutting and clamping mechanism is actuated, the pneumatic pressure delivered to cylinder 43 is increased sufficiently to aid in raising the head and associated apparatus until the head 41 is completely above the upper surface of the concrete. Such lifting of the apparatus is also effected by the Scotchyoke mechanism 48, in that the link 56 moves around the idler sprocket 61 (FIGURE 1) and causes the bearings 51 (FIGURE 4) to engage the under sides of collars 53 on shafts 36 to thus raise the shafts 36 and connected head by a distance approximately equal to the diameters of sprockets 60 and 61.

Particularly because the Scotch-yoke mechanism 48 simultaneously effects uniform deceleration in a horizontal direction and acceleration in an upward direction, the shock loads incident to lifting of the apparatus are relatively small. This is despite the fact that the speed of traverse may be rapid, on the order of 48 feet per minute or even very much higher.

Also at substantially the same time the cutting and clamping mechanism is operated, air pressure is delivered to reel brake 84 (FIGURE 5). Overtravel of the stripstorage reel 81 is thus effectively prevented.

The return traverse is then effected (right to left, FIG- URES 1 and 2) as the master link 56 moves with the upper run of drive chain 54. During this time, pressure is maintained in cylinder 114 (FIGURE 8) to hold the arms 100 and 101 in vertical positions and thus keep the projecting end of strip 10 clamped and properly oriented. As previously described, the strip 10 is not fed during such return traverse, because the one-way or overrunning clutch 117 (FIGURE 12) prevents driving of the feed roller 79 at this time despite rotation of sprocket 77 along stationary chain 76 (FIGURE 5).

As soon as the head 41 has been returned to the space above the road bed adjacent the inlet edge of the concrete, the air pressure in cylinder 43 (FIGURE 5) is bled substantially and therefore decreases to the requisite amount necessary to maintain the shoes 57 in floating relationship on the upper concrete surface. Such bleeding, and the downward movement of the master link 56 around drive sprocket 60, effect lowering of the head and associated apparatus until the shoes 57 (at their leading edge portions) engage the upper concrete surface. Such action is substantially shock free, because of the timed bleeding of the air pressure, and because of the previously-indicated operation of the Scotch-yoke mechanism 48 in effecting deceleration and then acceleration in a smoooth and uniform manner. At substantially the same time, the clamping cylinder 114 (FIGURE 8) is operated in a direction effecting upward pivotal movement of the arms 1% and 101 to the releasing positions shown in phantom lines. In addition, the braking operation of reel brake 84 is discontinued. The operation is then repeated to insert an aditional length of strip 10 into the highway.

During the described operations, the apparatus is continuously self-propelled or drawn ahead, for example by connecting the drawbar mechanism 26 (FIGURE 1) to the extruder or prime mover E. As described in detail above, the traversing speed of the carriage 32 is related precisely to the forward speed of the bridge because one of the bridge wheels 18 (FIGURE 3) is connected through timing chain 67 to the sprocket 68 which (FIGURE 11) determines the speed of drive sprocket 60 for chain 54. The hydraulic motor 63, which also actuates the drive sprocket 60, serves as a power booster but does not control the speed of drive.

The apparatus is thus operative to lay down sections of joint strip 10 in parallel relationship and at desired intervals. It is to be understood that the apparatus moves ahead during the entire time the carriage 32 traverses in the return or right-to-left direction, and that this determines the spacing between the sections of joint strip. The degree of spacing may be changed in various ways, one of which is by temporarily interrupting the drive for carriage 32 during the return traverse in order to increase the distance between joints. Also, for example, one of the gear boxes 69 and 70 (FIGURE 11) may be made to operate as a transmission, and the speed of return traverse varied as desired.

Referring next to FIGURE 14, a joint strip 10 is shown in section. Such joint strip forms, in combination with adjacent sections of highway 11, and also in combination with a crack 136 which forms in the highway beneath the joint strip after setting and curing of the concrete, a joint between adjacent highway sections. Particularly because the joint strip 10 is inserted to the proper depth in a uniform manner, the crack 136 is highly straight and regular in a horizontal direction. However, as viewed in the vertical direction (FIGURE 14) the crack is sufficiently irregular to effect the desired amount of interlocking between the adjacent concrete slabs. Thus, the elevations of the adjacent slabs relative to each other are maintained constant.

It is to be understood that setting and curing of the concrete causes the same to shrink by an amount which is greater than any expansion of the cured concrete during hot weather and after curing and setting are completed. Therefore, the resulting cracks 136 are sufficiently wide to compensate for expansion of the concrete during hot weather. It follows that there will never be any buckling of the adjacent concrete slabs. All need for sawing, thick joints, etc., is thus completely eliminated by the present method and apparatus.

Referring next to FIGURE 15, a pneumatic circuit 140 is schematically represented for effecting, automatically, the above-indicated operations of the pneumatic elements 43, 84, and 114. Such pneumatic circuit is supplied with air from source 27, via air-receiver frame element 23 and hose 29. The pneumatic circuit is controlled by valves (air buttons) 141 and 142. The valves, in turn, are controlled by actuators 143 which are mounted at suitable locations adjacent beam or track 12 (FIGURE 2). The relationships are such that the valves are operated at suitable times by actuators 143, in the manner of limit switches.

The track 12 may, if desired, be moved along the highway in skewed relationship, as distinguished from being generally perpendicular to the highway axis as shown in FIGURE 2. Such skewed relationship may be desirable, for example in instances where it is wanted to cause the inserted joint strip to be exactly perpendicular to the highway axis as distinguished from being oblique thereto. It is emphasized, however, that an oblique orientation of the joint is normally greatly preferred in order to minimize vibrations in vehicles passing over the highway.

It. is to be understood that, if desired, an additional span or track 12 may be provided between the trucks 13 and 14. Such additional track may have a second carriage mounted thereon, the purpose being to insert additional strips into the highway. For example, one strip-insertion head may lay strip during a carriage traverse from the left side of the highway to the right side thereof, whereas the second strip-insertion head (one the second track or span) may lay strip during its traverse from the right side of the highway to the left side thereof.

The idler sprocket 61 is preferably a mere disc (without teeth). The chain guides 62 should extend to a point closely adjacent such sprocket.

As best shown in FIGURE 16, the shoes 57 are arranged in V-relationship (having upturned leading edges). Thus, the concrete tends to mound up in the region of inserter head 41. There is therefore excess concrete available for troweling into the groove behind the head, so that there will be no voids adjacent the strip. A trowel portion 

